1. Field of the Invention 
The present invention relates to an inside rose liner for a door lock. In particular, the present invention relates to an inside rose liner for improving the torque-resistant capacity of the door lock. 
2. Description of the Related Art 
A typical door lock includes a main body having an inside seat and an outside seat, an inside rose liner securely mounted to the inside seat, an outside rose liner securely mounted to the outside seat, an inside rose, an outside rose, an inside handle, and an outside handle. The inside handle and the outside handle of lever type are convenient to the disabled. The inside seat includes two diametrically disposed grooves, and the inside rose liner includes two diametrically disposed protrusions respectively engaged in the grooves of the inside seat. Similar design is adopted in the outside seat and the outside rose liner. The door lock of such a structure is simple and has a low manufacture cost. Nevertheless, the torque resulting from the force applied to the lever type handle for opening the door is relatively greater than that of a knob type handle. The simple engagement of the grooves and protrusions between the respective rose liner and the respective seat is insufficient to resist the torque if lever type handles are used. As a result, the inner parts of the door lock using lever type handles are apt to be damaged. 
U.S. Pat. No. 6,302,457 discloses an easy-to-install door lock with improved anti-torque effect for the outside rose assembly, wherein the inside seat of the main body of the door lock includes an outer threading for threadedly  engaging with a pull-resisting ring. The inside seat further includes two diametrically disposed flat surfaces, and the inside rose liner includes a central hole having two diametrically disposed flat sections, allowing the inside rose liner to be mounted around the inside seat without the risk of relative rotation. The outside seat includes an outer threading for threadedly engaging with the outside rose liner. Further, the outside seat includes two diametrically disposed flat surfaces, and an anti-torque ring includes a central hole having two diametrically disposed flat sections, allowing the anti-torque ring to be mounted around the outside seat without the risk of relative rotation. 
U.S. Pat. No. 6,364,383 discloses an easy-to-install door lock with burglar-proof effect for the outside rose assembly, wherein each of the inside seat and the outside seat of the main body of the door lock includes two diametrically disposed flat surfaces. Further, the inside rose liner includes a threaded inner periphery for threadedly engaging with an outer threading of the inside seat. An anti-torque ring is engaged on the outside seat for improving the torque-bearing capacity. The anti-torque ring has a central hole having two diametrically disposed flat sections, allowing the anti-torque ring to be mounted around the outside seat without the risk of relative rotation. 
However, the threading arrangements of the door locks disclosed in U.S. Pat. Nos. 6,302,457 and 6,364,383 require additional processing and thus fail to provide a simple structure while resulting in an increase in the cost. 